In prior art disc saw felling heads, such as in U.S. Pat. No. 6,068,035, the saw housing is integral to the saw head frame weldment. The lower saw blade guards are bolted on a plane that is below the horizontal level of the saw blade.
During saw head operation, the saw blade ejects chips, dirt and other debris. The vertical walls of the saw housing enclosing the saw blade contain this ejected debris. In some regions, especially in the southeastern United States, this debris includes very abrasive sand that can erode the steel walls of the saw housing to the point that holes appear on the housing. Welding patches to the saw housing walls are typical repairs for these holes.
These repairs are expensive and can keep the machine out of service for long periods of time. Also, qualified service personnel are required to properly perform the repairs.
Very expensive hard facing has been added to the inside of the housing in an effort to improve the life of the components. This has greatly increased the cost of the housing, and when it eventually does wear through, the repairs are even more expensive.